The separation of CO2 gas from an exhaust gas low of a combustion system allows a reduced emission of CO2 into the atmosphere. This, especially against the background of state and interstate regulated reductions of emitted CO2, is an economical cost factor which is increasingly taken into consideration in the commercial future plans of many undertakings.
At the same time, such a CO2 separation method also enables the directed collection of CO2 gas which in turn can be fed as a source material to special process engineering operations. Consequently, CO2 can also be seen as a valuable base material. The “enhanced oil recovery” (EOR) process, for example, constitutes such a process for the technical use of CO2, in which CO2 is injected into underground rock layers of oil deposits so that it is released in the crude oil which is present in these oil deposits and at the same time brings about a viscosity reduction of the crude oil. On account of the viscosity reduction, the flowability of the oil is significantly increased and can therefore be extracted more easily from the rock structures with lower flow resistance. At the same time, the CO2 which is injected into the underground oil deposits serves for increasing the ambient pressure in the oil deposits, as a result of which a directional flow behavior of the crude oil, which has been changed with regard to its viscosity, can be achieved.
The CO2 gas which is introduced into the oil deposits currently originates predominantly from refining processes of the natural gas producing industry. Over recent years, it has been proved, however, that the costly transporting of CO2 produced in this way from the refinery sites to the oil deposits requires a sometimes large and expensive piping network. The provision of such a network, however, in turn greatly increases the costs for the CO2 and therefore the costs for the crude oil which is extracted with the aid of the CO2.
In this respect, a changeover has already been made in part to locating the natural gas processing in local proximity to the oil deposits. Since the crude oil extraction typically also delivers natural gas as a by-product, the natural gas which is produced there can be processed comparatively cost effectively and consequently CO2 can be produced comparatively more cost effectively.
Further efforts are directed towards separating CO2 from the combustion systems, which are operated for the oil extraction, in the regions of the oil extraction for power generation. The combustion systems, on account of the strong presence of natural gas in the regions of crude oil extraction, are mostly constructed as gas turbines. To this end, the combustion system is equipped with a suitable CO2 separation apparatus for the operation, wherein the CO2 which is produced by means of the CO2 separation apparatus can be further processed. Also, the CO2 which is produced in this way can be pumped under pressure directly into the oil deposits for improved oil yield. The equipping of the combustion system with a CO2 separation apparatus is typically carried out in this case by both components being designed and interconnected in an overall system, wherein both components are adapted to the respectively other component with regard to their operation.
Even if the combustion system, on account of the oxidative combustion taking place in it, can produce CO2 in comparatively large quantities, its separation in a downstream CO2 separation apparatus is possible only by means of an energy-intensive CO2 separation process. This additional consumption of energy on the one hand reduces the cost effectiveness of the CO2 which is produced in this way and, in addition, also appreciably reduces the overall efficiency of the system consisting of combustion system and CO2 separation apparatus.
Consequently, it is desirable to propose a suitable method for retrofitting an already existing gas turbine power plant with a CO2 separation apparatus, wherein the retrofitting method shall not limit the power output, especially the electric power output of the gas turbine. It is also desirable to retrofit an already existing gas turbine power plant in such a way that an efficient separation of CO2 from the flue gas of the gas turbine power plant is made possible. Retrofitting of a gas turbine power plant which allows an essentially energy-autonomous operation of a CO2 separation apparatus which is fluidically connected thereto is to be especially preferably made possible.